1. Field of the Invention
The present invention relates to extrudable igniter compositions, and specifically extruded ignition sticks, prills, pellets, and granules. More particularly, the present invention relates to providing sticks in combination with gas generant compositions suitable for use in gas bag inflators, such as supplemental safety restraint systems for vehicles, and related apparatus.
2. Background Information
Igniter compositions for supplemental safety systems, including "airbags," ought to satisfy a number of design criteria. The igniter composition, when formed, should be sufficiently robust to remain in operable form prior to deployment of a safety system, such as a passenger-protecting, driver-protecting, or side impact system. Consistent with the overall objectives of these and other types of safety systems, the igniter compositions are generally sought to be used in such amounts to avoid disposal problems and avoid generating by-products in amounts which pose other hazards following ignition.
Supplemental safety restraint systems have heretofore employed a number of different igniter systems. One of the commonly proposed igniter systems uses solid particles consisting of B/KNO.sub.3 which, when ignited, initiate combustion of the specified gas generant composition.
Other recent efforts have focused on developing alternative cost-effective igniter compositions or igniter compositions which are more easily manufactured. These efforts have included a proposal to use a hot-melt thermoplastic resin matrix together with a particular igniter composition, such as KNO.sub.3. This effort sought to marry a commercially available hot melt adhesive, such as one designed for so-called "glue-guns", with a common alkali metal oxidizer. This effort to improve performance was less than satisfactory. Extrudability and igniter performance proved difficult to control, and the repeatable ballistic performance desired for supplemental safety restraint systems has not yet been demonstrated.
Accordingly, despite these and still other efforts, commercially relevant objectives remain unattained. A simpler, more cost-effective igniter composition for supplemental safety restraint systems remains desired. In particular, efforts are still on-going towards providing an igniter composition which avoids the need for hot melting so-called adhesives, and thus the consequent risks associated with processing a pyrotechnic material at an elevated temperature, but which is facile to manufacture and would be sufficiently robust.
It would, therefore, be a significant advance to provide igniter compositions capable of being used to ignite gas generant compositions which satisfactorily address these concerns in the industry.